This invention relates to instruments for applying pressure and more particularly to jacks for trailer tongues.
Standard trailer tongue jacks sometimes pose two significant problems, interference with lowering of tailgates of towing vehicles and lack of effective security against theft. A trailer jack that allows for lowering of a tailgate while the trailer is attached to the vehicle is known. See, for example, U.S. Pat. No. 3,314,692. A vehicle jack with anti-theft features is known. See, for example. U.S. Pat. No. 5,782,115. It would be desirable to have a trailer jack with both features in a convenient combination.
In an exemplary embodiment, a trailer jack system for a trailer tongue is provided with convenient tailgate non-interference and convenient anti-theft features in a single package. The trailer jack system includes separable top and bottom housings which must be aligned and engaged to render the system operable for raising or lowering of a trailer tongue. The bottom housing is adapted to be permanently affixed to a trailer tongue. The top housing is rapidly and easily separable from the bottom housing for allowing a motor vehicle tailgate to be lowered while the trailer is attached to the motor vehicle and for providing security against theft of the trailer when the trailer is left unattached and unattended.
The top housing has a rotary driveshaft therein, a first coupling on a lower end of the driveshaft, the coupling having a first set of engagement surfaces of a non-standard shape. The bottom housing has a selectively downwardly extendable and retractable jack having a jackscrew with an upper end within the housing. A second coupling is provided on the upper end of the jackscrew. The second coupling has a second set of engagement surfaces of a non-standard shape configured to mate with and engage the first set of engagement surfaces. A releasable connector is provided for selectively, and rapidly connecting and disconnecting the upper and lower housings so as to securely maintain the engagement of the first and second couplings and yet allow for rapid disconnection to conveniently disengage the first and second couplings Optionally, a lockable cover for the bottom housing is provided to prevent unauthorized access to the second coupling